Abstract: Based on the characteristics of low permeability oilfield such as poor petrophysical property, varied lithology, complicated porosity texture and serious heterogeneity, etc., the formula for calculation of liquid productivity index and oil productivity index are presented with either starting pressure or multi-force effects, and the effect of oil-water viscosity ratio and starting pressure gradient on changes of such indices with water cut in low permeability oilfield is analyzed. The results show that the effect of water cut on the indices is bigger. In the case of same water cut, the higher the oil-water viscosity, the bigger the ratio between starting pressure gradient and production pressure gradient as well as the dimensionless liquid productivity index.

Key words: low permeability reservoir, liquid productivity index, oil productivity index, starting pressure, water cut, viscosity